Ep 13. From Bad to Worse

In season 3 episode 13 of Adventure Time titled "From Bad to Worse", the Land of Ooo faces a medical emergency when Princess Bubblegum gets infected with a zombie virus and turns into a brain-eating monster. Finn and Jake are tasked with finding a cure before the infection spreads to others and jeopardizes the kingdom.

The episode picks up with Princess Bubblegum conducting an experiment in her laboratory with the help of Finn and Jake. However, the experiment goes wrong when a rotten apple infects the Princess with a zombie virus, causing her to lose control and attack anyone in her sight. As Finn and Jake frantically try to contain the situation, the virus spreads to other citizens of Ooo, including the Candy People.

Finn and Jake soon realize that the virus is highly contagious and can turn anyone into a zombie, and that they need to find a cure as soon as possible before the entire kingdom is infected. They seek the help of Princess Bubblegum's trusted advisor, Doctor Princess, who informs them that the virus can be cured only by a rare type of soup, the ingredients of which are scattered across the land.

Finn and Jake embark on a perilous journey across Ooo to collect the ingredients for the soup, encountering several obstacles and zombies along the way. They come across the house of Tree Trunks, who has already been infected and turned into a zombie, and struggle to evade her attacks.

Meanwhile, back in the Candy Kingdom, Princess Bubblegum's condition worsens, and she starts to lose her memories and intelligence as she transforms into a full-fledged zombie. The Candy People lock themselves in their homes, but the virus still manages to spread, turning several of them into zombies as well.

Finn and Jake finally manage to gather all the ingredients and return to the Candy Kingdom, where Doctor Princess prepares the soup using a complicated recipe. They feed the soup to Princess Bubblegum, who regains her normal self within seconds. As the soup's effect spreads through the kingdom, all the infected citizens transform back to their original selves, and Ooo is saved from the zombie apocalypse.

The episode ends with Finn and Princess Bubblegum discussing the importance of containment in experiments and Finn expressing his gratitude for the happy ending. The episode serves as a reminder of the risks associated with experiments and the importance of being prepared for any unforeseen outcomes.